Preparation and structure of NHC Hg(ii) and Ag(i) macrometallocycles

Abstract

A series of functionalized bis-azolium salts, 1,8-bis[2′-(N-R-azoliumyl)ethoxy]-9,10-anthraquinone hexafluorophosphate L¹H₂·(PF₆)₂–L⁴H₂·(PF₆)₂ (R = Et, CH₂Ph and CH₂Py, azoliumyl = benzimidazoliumyl or imidazoliumyl), as well as their seven N-heterocyclic carbene mercury(II) and silver(I) complexes [(L²HgBr)₂](HgBr₄) (1), [L²Hg(HgI₄)]₂ (2), [L¹Hg(HgI₄)] (3), [L⁴Hg(HgI₄)] (4), [L¹Ag](PF₆) (5), [L³Ag](PF₆) (6) and [L⁴Ag](PF₆) (7) have been prepared and characterized. In complexes 1 or 2, two 16-membered macrometallocycles are connected together via two bridging halide ions (two bridging bromide ions for 1, and two bridging iodide ions for 2). In complexes 3–7, each molecule contains one 16-membered macrometallocycle formed by one biscarbene ligand (L¹ for 3 and 5, L³ for 6, L⁴ for 4 and 7) and one metal ion (Hg(II) for 3 and 4, Ag(I) for 5–7). In the crystal packings of 1–7, 2D supramolecular layers and 3D supramolecular architectures are formed via intermolecular weak interactions (such as the hydrogen bonds, π–π interactions and C–H⋯π contacts). In addition, the fluorescence emission spectra of the complexes and bis-azolium salts were described. The cyclic voltammetry study for silver(I) complexes 5–7 was conducted.